Method for providing nonoxidizing atmosphere



Patented Jan. 16, 1940 METHOD FOR PROVID ATMOS ING NON OXIDIZIN G PHERE Raymond J. Wean, Warren, Ohio, assignor to The Wean Engineering Company, Inc., a corporation of Ohio Application July 18, 1938, Serial N0. 219,936

2 Claims.

This invention relates to the provision and maintenance of a nonoxidizing atmosphere wherever such atmosphere is desired.

The use of nonoxidizing atmospheres in metallurgical operations is quite common. It has been customary heretofore to provide and maintain such atmosphere by installing a gas generating system withl the necessary piping connections extending therefrom to the various points where the gas is to be used. In the case of portable annealing furnaces, exible connections are also required between the ends of the pipe lines and the furnaces themselves. Numerous objections to this arrangement have been experienced in practice. In the rst place, the cost of a gas generating and distributing system is considerable. In the second place, skilled operators are required to handle the generating equipment. In the case of portable furnaces, furthermore, a s pecial operator is required to make and break the hose connections between the pipe lines and the furnaces, to prevent the hazard of asphyxiation and explosion. In spite of the greatest care, furthermore, leakage of gas sometimes occurs because the separable connections become loosened so that the gas is apt to ll the mill building instead of the furnace.

I- have invented a method and apparatus for providing and maintaining a nonoxidizing atmosphere for metallurgical and other purposes which avoids the aforementioned objections. In a preferred form of the invention, I dispose within a furnace or other enclosure, a small container having compressed nonoxidizing gas therein, or a material capable of evolving such gas. Since most metallurgical operations are conducted at elevated temperatures, I provide means for releasing the nonoxidizing gas or the material. which generates it in response to increased temperature of the container. A fusible plug is one example of such means for releasing such gas or gas gene erating material. An alternativs is the suspension of a frangible container on a fusible or combustible wire, string or the like so that the container is shattered on falling, to release the gas or gas generating material.

The invention will be described in detail with reference to the accompanying drawing illustrating a method of making sheet metal in which the invention is particularly applicable, although this is merely one example of many. In the drawlng:

Fig. 1 illustrates diagrammatically the hot roll- Ing. of a slab or billet into strip'orm;

Fig. 2 is a central vertical section through one form of apparatus embodying the invention;

Fig. 3 is a similar view of a modification; and

Fig. 4 is a diagrammatic illustration indicating the further processing of the strip.

Referring in detail to the drawing, a slab or billet I0, after being heated to the proper temperature, may be reduced to strip form by passing it through a continuous mill including, for example, two 2-high stands I2 and four 4-high l0 stands I3. After passing through a continuous mill of this character,-the billet I is reduced to the form of strip as indicated at I3. By means of a coiler I5 of known construction, the strip emerging from the mill is 'coiled tightly. l5

In my copending application Serial No. 226,510 led August 24, 1938, for Method of making sheet metal, I have described and claimed a method of making sheet metal including the step of protecting hot rolled strip coiled as it leaves the last zo stand of a continuous mill, from oxidation while cooling by placing it within an enclosure and maintaining a nonoxidizing atmosphere therein. Fig. 2 illustrates one formA of apparatus for performing this operation including a charge supporting base I I having a peripheral sealing channel I8 and an open-bottomed bell-shaped enclosure or cover I8. The cover I9 has hooks 20 welded thereto to facilitate lifting by a crane. 'I'he top of the cover indicated at 2| has an open- 30 ing 22 formed therein surrounded by a peripheral sealing channel 23. A closure 24 is removably seated in the channel 23.

In order to provide a nonoxidizing atmosphere within the cover I9, I suspend a cartridge 25 from 35 the closure 24 by a combustible or fusible suspension 26, before lowering the cover over the coil and base. 'I'he cartridge may take any convenient form and may be of such construction as to release its contents when subjected to the heat 40 of the coil, or may be frangible so that its contents are released when it falls onto the base, as indicated in dotted lines, after fusion or combustion of the suspension 26. The atmosphere producing content of the cartridge maybe turpentine, kerosene or the'llke which produce hy# drocarbon gases such as CO and CO2 upon combustion. Other combustibles which may be used are propane gas or carbon in the form of charcoal. Alternatively, the cartridge may contain a neutral gas such as nitrogen under pressure or a chemical such as phosphorus.

As the cover I9 is lowered over the coil, a certain amount of atmospheric air is trapped therein. The oxygen content of this air quickly combines with the turpentine or kerosene, in the combustion thereof, or with the phosphorus, in the oxidation thereof. If the cartridge contains a compressed neutral gas, the latter purges the cover I9 of air by forcing it out through the seals contained in the channels I8 and 23. The nonoxidizing gases generated by the combustion of the turpentine or kerosene or the release of the neutral gas ow upwardly through the coil and downwardly therearound with a wiping action, as indicated by the arrows 21, thus driving out the atmospheric oxygen and protecting the coiled strip from further oxidation.

Figure 3 illustrates a modified form of cover I9 having inner and outer walls 28 and 29, respectively, between which thermal insulating material 30 is disposed. Otherwise, the co'ver I9' is similar to the cover I9. Because of the insulation 30, a coil I6 enclosed therein cools more slowly than a coil disposed Within the cover I9.

When the hot-rolled strip has cooled substantially to atmospheric temperature, it may be reduced to final gauge by cold rolling in a mill such as that illustrated diagrammatically at 3| in Fig. 4. As there shown, the mill comprises four fourhigh stands through which the hot-rolled strip passes continuously from an unwinding reel to a rewinding reel. It willbe understood, of course, that the mill indicated diagrammatically at 3l is purely illustrative. Should the material require only such reduction as may be effected on a single stand, it will be unnecessary to pass the material through a continuous mill.

It will be understood that the forms of apparatus shown in Figs. 2 and 3 are merely illustrative examples. The invention may likewise be applied to stationary enclosures having doors for the admission and removal of the material being treated. As previously stated, furthermore, the container 25 may be provided with a fusible plug which will be melted by the heat of the coil to release `the nonoxidizing gas or the gas producing material. In such case, the container 25 need not be suspended in the container but may be merely placed on the base Il or on the floor of a fixed enclosure if such is usually employed.

Numerous advantages of my invention will be recognized immediately. In the rst place, it makes possible a material reduction in the cost of providing and maintaining a nonoxidizing atmosphere. The containers 25 may obviously be manufactlured at relatively low cost so that leven if they are used in considerable numbers, the total expense will not approach that of installing and maintainingA a gas generating and distribution system. A further advantage is that there are no live connections such as hose or pipe lines to be attached to or removed from the enclosure in case of a portable cover such as those illustrated in the drawing. Since no particular skill is required in handling the containers 25, any workman at the scene of operations can place the container in position either before or after the coil is delivered to the point of cooling. The invention also eliminates the necessity for a special operator to manipulate the connections, valves, etc. as has been necessary heretofore.

Since the non-oxidizing gas is released only after the enclosure has been sealed, the danger of asphyxiation or explosion is negligible. At the completion of the operation, the lifting of the cover I9, for'example, permits the nonoxidizing gas trapped therein to be dissipated upwardlv almost instantaneously. Since the supply of nonoxidizing gas is limited, there is no danger such as is involved by a leaky joint in a distribution system connected to a continuously operating gas generator.

Although I have illustrated and described herein but a preferred form and practice of the invention, it will be recognized that other structures and procedures may be employed without departing from the spirit of the invention or the scope of the appended claims.

I claim:

l. In a method of making sheet metal by hotrolling a slab into strip while exposed to the atmosphere, and coiling the strip in the air while hot from'the rolling, the steps including substantially immediately disposing the coil of strip in an enclosure, and placing in said enclosure means adapted to supply a nonoxidizing uid therein when subjected to the heat from said coil.

2. In the manufacture of hot-rolled strip by rolling a heated slab in air and coiling the strip in air while hot, the steps of substantially immediately disposing the coil of strip in an enclosure, and placing in said enclosure material adapted to supply a nonoxidizing atmosphere therein when subjected to the heat from the coil.

RAYMOND J. WEAN. 

